Apparatus for starting a pulsatory combustion device



Aug. 25, 1959 E. REIMERS O 2,900,790

APPARATUS FOR STARTING A PULSATORY COMBUSTION DEVICE Filed NOV. 1, 1955UVVENTUR: Evn+ PQmkers Unite States Patent APPARATUS FOR STARTHNG APULSATORY COMBUSTION DEVICE Ernst Reimers, Wernau am Neckar, Germany,assignor to Junkers & Co. G.m.b.H., Wernau, Neckar, Germany ApplicationNovember 1, 1955, Serial No. 544,305

Claims priority, application Germany N oveinber 2, 1954 Claims. (Cl.60-'--39.77)

The present invention relates to pulse jet combustion devices, and moreparticularly to an apparatus for starting a pulse jet combustion device.

In known pulse jet combustion devices it is necessary to providecompressors or pumps for supplying to the combustion chamber acombustible fuel-air mixture for starting the device, and besides theadditional source of energy required for such auxiliary devices, it isnecessary to provide the combustion chamber with a special opening toreceive the fuel-air mixture for starting purposes, and such an openingis very undesirable because the greater the number of openings in thecombustion chamber the less is the average top pressure in thecombustion chamber and therefore the smaller is the vacuum force whichis available for sucking in a combustible mixture for the successiveimpulses during normal operation.

One of the objects of the present invention is to provide a pulse jetcombustion device which does not require a special supply structure forsupplying the pulse jet combustion device with a combustible mixture forstarting the device.

Another object of the present invention is to provide an arrangementwhere one of the resonant tubes used during the normal operation of thepulse jet combustion device also serves to convey to the combustionchamber a combustible fuel-air mixture for starting purposes.

A further object of the present invention is to provide a pulse jetcombustion device which requires no outside power or source ofcompressed air or the like for starting purposes.

An additional object of the present invention is to provide anexceedingly simple and inexpensive structure for starting a pulse jetcombustion device.

Also it is an object of the present invention to provide a pulse jetcombustion device which requires no special opening in the combustionchamber for receiving a combustible fuel-air mixture for startingpurposes.

With the above objects in view the present invention mainly consists ofa pulse jet combustion device which includes a combustion chamber and anexhaust chamber spaced from the combustion chamber. A plurality ofresonant tubes each communicate at one end with the combustion chamberand at its opposite end with the ex haust chamber. A means cooperateswith one of said resonant tubes for supplying through the latter acombustible fuel-air mixture to the combustion chamber for starting thedevice.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

Referring now to the drawing, it will be seen that the pulse jetcombustion device illustrated therein includes a fuel supply tube 1provided with an inlet valve 2 which "ice permits fuel to be sucked fromthe supply tube 1 along the tube 5 intothe interior of the combustionchamber 6. The tube 5 also communicates with an air inlet valve 4 havingan inlet end 3 through which air may be sucked into the tube 5 formovement into the combustion chamber 6. As is apparent from thediagrammatically illustrated structure of the drawing, during the normaloperation of the pulse jet combustion device a suction force in thecombustion chamber will automatically draw air and fuel through theabove described structure into the combustion chamber to be explodedtherein.

The combustion chamber 6 is formed with an ignition opening 7 adjacentwhich is located a tube 8 supplied with a combustible gas so that thisgas may be ignited to form a flame 9 located. adjacent the opening 7 forigniting a combustible fuel-air mixture in the combustion chamber 6 forstarting the device.

In accordance with the present invention a plurality of resonant tubescommunicate with the combustion chamber 6, and in the illustratedexample two tubes 10 and 10 are shown. These tubes 10 and 10comrnunicateat their ends opposite irom the combustion chamber 6 with a commonexhaust chamber 11.

According to the present invention a combustible fuelair mixture issupplied through one of the resonant tubes 10 and 10 into theinterior-of the combustion chamber 6 for starting purposes and aninjector means 12-14 is provided for injecting through one of theseresonant tubes the combustible fuel-air mixture which is delivered tothe combustion chamber 6. Thus, this injector means includes aVenturi-shaped tubular member 12 carried by a wall of the exhaustchamber 11-, extending slightly outwardly beyond the same, and extendingalong the interior thereof to a point closely adjacent the end of thetube 10 which. communicates with the chamber 11. Thus, the Venturi 12has its inlet end located at the exterior of the exhaust chamber 11 andits outlet end located adjacent the end of the tube 10 whichcommunicates with the exhaust chamber 11. The nozzle 13 is aligned withand spaced from the inlet end of the Venturi 12, and a combustible fuelis supplied by the conduit 14 to the nozzle 13. p

A11 exhaust tube 15 leads from the common exhaust chamber 11.

As will be apparent from the description below a plurality of resonanttubes, such as the tubes 10 and 10, are of advantage because one ofthese tubes simultaneously serves to conduct to the exhaust chamber acombustible fuel-air mixture for starting purposes. How ever, such aplurality of resonant tubes are of further advantage. Thus, two tubes 10and 10', as shown in the drawing, are superior to a single tube whosecross section is equal to the total of the cross sectional areas of thetubes 10 and10', because a pair of such tubes of smaller cross sectioncan be bent along a smaller radius.

The above described structure operates as follows.

In order to start the pulse jet combustion device, the combustible fuelis supplied by the conduit 14 to the nozzle 13 and streams from thelatter to the air-gap between elements 12 and 13 into the inlet end ofthe Venturi 12. As the combustible fuel streams cross the gap, itautomatically sucks air With itself into the Venturi 12, and fromtheVenturi 12 this combustible fuel-air mixture enters into the tube 10 andmoves along the latter into U s the device is started the maincombustible fuel is automatically sucked in through the supply pipe 1and valve 2 and the main air is sucked in through the inlet 3 and valve4 and along the tube 5 into the combustion chamber 6. The combustiblemixture which is in this 'way supplied to the tube displaces fromthelatter gases previously located therein, and these displaced gases moveinto the combustion chamber 6 to be displaced with the gases in thelatter along the tube 10' back into the exhaust chamber 11, in themanner described above. Thus, it will be seen that where an installationincluding a plurality of resonant tubes, such as the tubes 10 and 10',is provided, it is possible with the present invention to use one of ofthese resonant tubes to serve the additional purpose of conducting tothe interior of the combustion chamber a combustible mixture forstarting purposes, and in this way a special structure for guiding thestarting mixture to the combustion chamber is unnecessary. Furthermoreit will be seen that special compressors or pumps or the like forstarting purposes also are unnecessary. It will be noted that the flame9 continues to burn during normal operation.

The invention is also usable with pulsating jet combustion devices whereonly aerodynamic means, such as, for example, dilfusors, nozzles, returnflow throttles, and the like are provided for supplying the combustiblemixture. This aerodynamic means is intended for the normal operation.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofpulse jet combustion devices differing from the types described above.

While the invention has been illustrated and described as embodied instructure for starting pulse jet combustion devices, it is not intendedto be limited to the details shown, since various modifications andstructural changes may be made without departing in any Way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a pulse jet combustion device, in combination, a combustionchamber; an exhaust chamber spaced from said combustion chamber; aplurality of resonant tubes each communicating at one end with saidcombustion chamber and at its opposite end with said exhaust chamber;and injector means cooperating with one of said tubes for transmittingthrough the latter to said combustion chamber a combustible fuel-airmixture for starting the device, said injector means comprising atubular member carried by said exhaust chamber and extending into thesame, said tubular member having an inlet end at the exterior of saidexhaust chamber and an outlet end located closely adjacent to the end ofsaid one of said tubes which communicates with said exhaust chamber, andsaid injector means including a nozzle aligned with and spaced from theinlet end of said tubular member and located at the exterior of saidexhaust chamber and a conduit communicating with said nozzle forsupplying to the latter a combustible fuel which passes through the freespace between said nozzle and tubular member into the latter to supplythrough said tubular member fuel and air drawn into said tubular memberthrough said space which then pass through said one of said tubes intosaid combustion chamber.

2. In a pulse jet combustion device, in combination, a combustionchamber; an exhaust chamber spaced from said combustion chamber; aplurality of resonant tubes each of which communicates at one endthereof with said combustion chamber and at its opposite end with saidexhaust chamber, said combustion chamber, tubes and exhaust chamberforming together a resonant burner system in which the exhaust gasespass through said tubes in one direction from said combustion chamber tosaid exhaust chamber; and starting fuel supply means supplying acombustible fuel-air mixture only during starting of said device, saidstarting fuel supply means communicating with one of said tubes spacedfrom the combustion chamber for propelling through said tube and in adirection opposite to said one direction into the combustion chamber, acombustible starting fuel-air mixture for starting the device, wherebyduring the starting period exhaust gas present in said combustionchamber may be expelled by the introduced starting combustion fuelairmixture through the other of said resonant tubes.

3. In a pulse jet combustion device, in combination, a combustionchamber; an exhaust chamber spaced from said combustion chamber; aplurality of resonant tubes each of which communicates at one endthereof with said combustion chamber and at its opposite end with saidexhaust chamber, said combustion chamber, tubes and exhaust chamberforming together a resonant burner system in which the exhaust gasespass through said tubes in one direction from said combustion chamber tosaid 7 exhaust chamber; and starting fuel injector means supplyof one ofsaid resonant tubes for propelling through said tube and in directionopposite to said one direction into the combustion chamber a combustiblestarting fuel-air mixture for starting the device, whereby during thestarting period exhaust gas present in said combustion chamber may beexpelled by the introduced starting combustion fuel-air mixture throughthe other of said resonant tubes.

4. In a pulse jet combustion device, in combination, a combustionchamber; an exhaust chamber spaced from said combustion chamber; aplurality of resonant tubes each of which communicates at one endthereof with said combustion chamber and at its opposite end with saidexhaust chamber, said combustion chamber, tubes and exhaust chamberforming together a resonant burner system in which the exhaust gasespass through said tubes in one direction from said combustion chamber tosaid exhaust chamber; main fuel supply means for supplying a combustiblefuel-air mixture after starting of the device directly into saidcombustion chamber; and additional starting fuel supply means supplyinga combustible fuel- 1 air mixture only during starting of said device,said ad- 'ditional starting fuel supply means communicating with one ofsaid tubes spaced from the combustion chamber for propelling throughsaid tube and in direction opposite to said one direction into thecombustion chamber a combustible starting fuel-air mixture for startingthe device, whereby during the starting period exhaust gas present insaid combustion chamber may be expelled by the introduced startingcombustion fuel-air mixture through the other of said resonant tubes.

5. In a pulse jet combustion device, in combination, a combustionchamber; an exhaust chamber spaced from said combustion chamber; aplurality of resonant tubes each communicating at one end thereof withsaid combustion chamber and at its opposite end with said exhaustchamber; and injector means cooperating with at least one but not all ofsaid resonant tubes for transmitting through at least one of saidresonant tubes to said combustion chamber a combustible fuel-air mixturefor starting the device, said injector means comprising at least onetubular member carried by said exhaust chamber and extending into thesame, said tubular member having an inlet end at the exterior of saidexhaust chamber and an outlet end located closely adjacent to the end ofone of the resonant tubes cooperating with said injector means andcommunicating with said exhaust chamber, and said injector meansincluding at least one nozzle aligned with and spaced from said inletend of said tubular member and located at the exterior of said exhaustchamber and conduit means communicating with said nozzle for supplyingto the latter a combustible fuel which passes through the free spacebetween said nozzle and tubular member into the latter to supply throughsaid tubular References Cited in the file of this patent UNITED STATESPATENTS 2,715,436 Lafierentz et al Aug. 16, 1955 FOREIGN PATENTS 966,563France Mar. 8, 1950

